As a trainer at CES Performance outside Atlanta for the past 12 years, Aaron Roberts is familiar with the offseason rhythms of most NFL players.

Those who return for workouts as early as February, he knows, tend to dip their toe back into training.

So Roberts was surprised last week when 49ers quarterback Colin Kaepernick arrived nine days removed from the Super Bowl with a question: What position group works the hardest?

The linemen? Guess which newly minted NFL glamour boy immediately began laboring with the big boys in the trenches?

"He's definitely not a prima donna," Roberts said. "He's not asking for special treatment. He wants to work out with the linemen, for crying out loud. He wants to get in the mix right off the bat. When I first heard he would be here so soon, I was like, 'OK, man, go take a vacation for a minute.' But I guess he's going to put that on hold."

Wrong. Kaepernick already took his vacation.

It lasted a week and included a trip to Southern California to attend the Cartoon Network Hall of Game awards and a pre-Grammy event in Beverly Hills.

After those red-carpet shindigs, it was bye-bye, Hollywood.

Hello, hard work.

Known for his 6 a.m. arrivals at the 49ers' facility during the season, Kaepernick is logging eight-hour training sessions five days a week at the CES facility in Duluth, Ga. His workouts include running, lifting and high-intensity swimming in which he's tethered to a resistance-providing harness.

By his standards, he's coasting. Clock-in time: 8 a.m.

His dive-right-back-in approach might have surprised Roberts, but others saw this type of offseason coming. Two days after the Super Bowl loss to the Ravens, a still-seething Kaepernick was asked how long the defeat would linger.

"For the rest of my life," he said.

Seeking a cheerier subject, a reporter asked what he would remember most about a season in which he threw for 302 yards in the Super Bowl, a game that came 77 days after his first NFL start.

"It wasn't good enough," Kaepernick said.

Moments later, left tackle Joe Staley was asked about his quarterback's quiet fury.

"He's probably one of the most competitive people I've ever been around," Staley said. "He has all the fuel he needs for a lifetime."

Said wide receiver Kyle Williams: "Being that close and not being able to get it? That guy is going to go crazy in the weight room. He's going to go crazy out there on the field."

Not surprisingly, Kaepernick is training with athletes who might be able to match his motivation: The majority of the players at CES this month have been hungry college prospects preparing for this week's NFL combine in Indianapolis.

This early in the NFL's offseason, Kaepernick is among a handful of professional players at CES. That group includes 49ers wide receivers Ricardo Lockette and Chad Hall, who both grew up in Georgia. Wide receiver A.J. Jenkins is expected to arrive soon, joining other pros such as Steelers linebacker Jason Worilds and his teammate, defensive tackle Steve McLendon.

Kaepernick also trained at CES before his senior season at Nevada and prior to the 2011 NFL combine. Before the '11 draft, CES founder Chip Smith was sufficiently impressed. Smith declared Kaepernick was more athletic, had a stronger arm and was more NFL-ready than Auburn's Cam Newton, another CES client who was the No. 1 overall pick in that year's draft.

Two years later, Kaepernick, taken 35 picks after Newton, has proved himself on the NFL's biggest stage. And he'll have to do it again next season against defenses that will be better prepared to limit the pistol offense Kaepernick runs brilliantly.

There will be pressure to duplicate his feats from his first season as a starter. In Kaepernick's mind, however, he's eliminating the issue of nerves by punching in each weekday morning in Duluth, Ga.

As he repeatedly said during a season in which he went from backup to bona fide star, pressure comes from a lack of preparation.